A liquid crystal display device is a kind of display device and includes a liquid crystal display panel including a pair of substrates (e.g., an active matrix substrate and a counter substrate) facing each other with a liquid crystal layer therebetween. Such a liquid crystal display device is being used in various applications, and its performances are being more and more improved. Particularly, display modes (liquid crystal modes) that permit wide viewing angle characteristics such as MVA (multi domain vertical alignment) mode have been developed, and a liquid crystal display device in such display modes is being further improved.
In order to improve display qualities of the liquid crystal display device, it is necessary to control the thickness of a liquid crystal layer (hereinafter, also referred to as a “cell gap”) precisely regardless of the display mode. Particularly in a large-sized liquid crystal display device that becoming more and more used now, the cell gap needs to be controlled to be uniform over a very large region.
The cell gap is controlled by a spacer that is arranged between the pair of substrates. A fiver or particle spacer (for example, plastic beads) has been used as a common spacer, and such a spacer is arranged by being sprayed on the substrate. However in such a case where spacers such as plastic beads are sprayed, the position where the spacers are arranged can not be controlled, and so liquid crystal molecules in a pixel (pixel opening) might not be aligned in proper directions. In a pixel where the liquid crystal molecules are not aligned in proper direction, variation is observed. In addition, if such a spacer is used, a base layer that is formed on the substrate has irregular surface, and thereby the cell gap varies. This variation in cell gap causes uneven display.
A method in which a column spacer is formed on a substrate by photolithography using a photosensitive material are now being used. Such a spacer is also referred to as a column spacer (photo spacer).
FIGS. 11 and 13 are cross-sectional views of conventional liquid crystal display panels and each schematically show a configuration around a region where a column spacer is arranged. As shown in FIG. 11, a method in which a resist for spacers is formed to give a column spacer 117a separately from other layers is commonly used for forming the column spacer. In addition, as shown in FIG. 13, a column spacer 117b composed of stacked color filters (colored layers) and the like (hereinafter, also referred to as a “multi-layer spacer”) is also used (for example, such a spacer is disclosed in Patent Documents 1 to 3).
High-frequency driving is now being researched and developed for improvement in moving image display and for higher definition. However, conventional liquid crystal display devices can not be driven at high-frequency because a parasitic capacitance, which is generated in a liquid crystal panel, deforms a signal waveform.
For this problem, in order to decrease a capacitance that is formed at an intersection between a scanning wiring and a signal wiring, a spin-on glass (hereinafter, also referred to as a “SOG”) material is arranged between the scanning wiring and the signal wiring (for example, refer to Patent Document 4).
[Patent Document 1]
Japanese Kokai Publication No. 2001-100221
[Patent Document 2]
Japanese Kokai Publication No. Hei-11-248921
[Patent Document 3]
Japanese Kokai Publication No. 2006-38951
[Patent Document 4]
WO 2006/022259